This quest appears to be bugged, to some extent. A group of us were progressing through the Roost - two chars were able to complete the quest, two others were not. Content: Visit the Queen's home and look for something to steal We were all given the update when we visited the birdcage, but the ground spawn only appeared for two characters (both inside birdcage). After an hour or so, we called it a night. Next day - still no ground spawns. Removed and reset/readded the quest for the two who still need ground spawn. Returned to Queen island and again received the update, but no ground spawns. Rinse/Repeat. Logged on new characters and started again - all chars get the update, but no ground spawns, still. The ground spawns are either spawning under the birdcage, or ?? They definitely are not spawning on the ledges or anywhere visible on the ledge/island.
Had the 2 persons who are not able to get them already done this portion long ago and forgot? Have they done all the ones before? This is what happened on some of my characters, it was so long ago I forgot but nothing spawns for them even though it says the quest is repeatable.
So this is what we discovered, and how we "fixed" it. If you remove the quest before ever starting it, it will be bugged. You will be able to receive the quest again and get the update for exploring the Queen's home, but the ground spawn will never appear. To get around this, we had two people who had successfully completed the quest start it again. We all went up to the ledge, they received their flags and the ground items spawned for them - we picked them up with the two characters they wouldn't spawn for. I'm sure those two characters are now bugged, though I doubt we will ever want to repeat this - but - there's an issue with it if we do.
